Re:GT 1600 Jr. M tuning procedure (longish)

[christian147@xxxxxxxx]

Hi, Jacob
>Does the fact that the valves are tight have much influence on the 
>emissions? What happens when the valvetrain wears - do the gaps get 
>smaller or larger normally?

Yes tight valves have a profound impact on emissions.  It is the came as
having a cam with longer duration, the valves are open longer so the
intake and exhaust flow need inertia and wave action to keep them moving
in the right direction, but its not there till the engine is at a higher
RPM, so at lower RPM you get more exhaust reversion up the intake and
more unburned fuel out the exhaust valve before it closes.  You can't
tune a carb till the valve timing is right.
  
Valve train wear depends on what you call wear.  Wear in its classic
since would open the clearance, valve seats being banged down by a lack
of lead on a soft seat causes them to close.  The first ALFA engine I saw
with hard valve seats was the first Motronic spider (1989?), before that
exhaust seat recession was common.  

Make sure you have fresh gas, gas is good for 90 days from refining, and
it takes 30 days to deliver it to the retailer, so figure it the gas has
been in the car for 60 days its degrading notable ( a fuel chemist told
me that).  Make sure you have the right weight of fresh oil in the
engine.  On an older motor you may need heaver oil to help seal the
rings, I have used up to 50% Lucas oil stabilizer or 70wt oil form the HD
dealer to get cars passed emission testing.  If the car is running rich
the oil may be diluted with gas and as it vaporizes the PVC system
returns it to the intake making it even richer.

Hotter spark plugs only help if they don't cause detonation.  If a car
detonates it makes NOX !  

Good luck
Chris Hall
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